arr.sort() : 배열 재정렬, 배열 자체가 변경되니 주의
let arr = [1, 5, 4, 2, 3];
arr.sort();
console.log(arr);
let arr = ['a', 'g', 'f', 'c'];
arr.sort();
console.log(arr);
let arr = [27, 8, 5, 13];
arr.sort();
console.log(arr);
let arr = [27, 8, 5, 13];
function fn(a, b){
console.log(a, b);
return a - b;
}
arr.sort(fn);
console.log(arr);
arr.reduce() : (누적 계산값, 현재값) ⇒ {return 계산값};
let arr = [1, 2, 3, 4, 5];
let result = 0;
arr.forEach(num => {
result += num;
});
console.log(result);
const result = arr.reduce((prev, cur)=>{
return prev + cur;
}, 0);
console.log(result);
let userList = [
{ name: "Mike", age: 30 },
{ name: "Tom", age: 10 },
{ name: "Jane", age: 27 },
{ name: "Sue", age: 26 },
{ name: "Harry", age: 42 },
{ name: "Steve", age: 60 }
];
let result = userList.reduce((prev, cur)=>{
if(cur.age > 19) {
prev.push(cur.name);
}
return prev;
}, []);
console.log(result);
let result = userList.reduce((prev, cur)=>{
return (prev += cur.age);
}, 0);
console.log(result);
let result = userList.reduce((prev, cur)=>{
if(cur.name.length === 3){
prev.push(cur.name);
}
return prev;
}, []);
console.log(result);